* NZ govt working on further fiscal support
* Treasury says jobless rate could hit 26% if lockdown extended
* Four new deaths from COVID-19 on Tuesday (Recasts and updates throughout with minister's comments on fiscal support, latest health ministry information on COVID-19 cases and bullet points)
By Praveen Menon
WELLINGTON, April 14 (Reuters) - The New Zealand government said on Tuesday it will unveil further fiscal stimulus this week as it forecast a surge in the unemployment rate to 26% if tough lockdown measures to fight the spread of the coronavirus are extended.
New Zealand's offices, schools and non-essential services have been closed for the last three weeks, with the country experiencing one of the strictest lockdowns globally.
The government is expected to decide next week whether it will extend that current Level 4 shutdown, which is the highest ranking on the scale. If it does so, Treasury has forecast it would increase unemployment to between 17.5% to 26% from the current 4%.
Mapping economic scenarios from the lowest restriction level to the highest, the Treasury said declines in annual gross domestic product in the year ending March 2021 would vary from around 13% to close to one-third.
Finance Minister Grant Robertson said work on further government investment to protect jobs, support cash flow, and prepare the economy for recovery was "well advanced".
"The next steps in the government's plan to support businesses will be released later this week," he said in a statement after the Treasury forecasts were released.
Robertson said unemployment could be kept below 10%, and return to 5% in 2021 with additional government support. The economy could bounce back to be NZ$70 billion ($42.62 billion) larger by 2024 than in 2019, Robertson said.
The government has already announced fiscal measures, including wage subsidies and support for small businesses, of around NZ$20 billion.
Treasury estimated GDP falling around 25% in the June quarter, followed by a 20% rise in the September quarter if, rather than continuing with Level 4 restrictions, a greater range of economic activities was allowed to resume.
PASSED PEAK
Despite having fewer COVID-19 infections than many other countries, Prime Minister Jacinda Ardern's government enforced a one-month lockdown in a bid to completely eliminate the disease from the country.
New Zealand on Tuesday recorded four additional deaths related to COVID-19, the disease caused by the new coronavirus, taking the total to nine deaths in the country. It has recorded 1,366 cases of infection.
But the number of new cases has stayed significantly low since the lockdown and the health ministry said it was confident the country had passed the peak.
"We have passed the peak, that seems to be clear now," Ashley Bloomfield, the director general of health said in a news conference.
"We will be more confident once we know more about each of those new cases that has been occurring in the past week," he added.
($1 = 1.6426 New Zealand dollars)